Aramid insulation paper, preparation method and application

Abstract

The present invention discloses aramid insulation paper, a preparation method, and applications, relating to the technical field of aramid paper. The present invention utilizes cellulose treated with a treatment agent A and aminosulfonic acid in combination with meta-aramid chopped fibers treated with the treatment agent A to produce aramid insulation paper with excellent mechanical properties and resistance to high-frequency partial discharge and high temperatures.

Description

Technical Field

[0001] The present invention relates to the technical field of aramid paper, in particular to aramid insulating paper, a preparation method and application thereof. Background Art

[0002] With technological advancements and the increasing electronicization and intelligence of power systems, high-frequency transformers, core electrical equipment, are facing challenges in achieving higher frequencies, higher power densities, and smaller and lighter weights. This is particularly true for power converters connected to high-frequency transformers, which are experiencing bottlenecks and can reach frequencies of 100 kHz or even higher. This leads to more severe field concentration and heat dissipation issues in the inter-turn insulation of high-frequency transformers, leading to premature failure. Aramid paper, the primary insulating material for high-frequency transformers, is susceptible to partial discharge and high temperatures, which can cause premature failure. Therefore, various methods are being used domestically to improve the performance and reduce the cost of aramid insulation paper. Plant cellulose, with its high aspect ratio and large surface area, has abundant surface hydroxyl groups that can bind to a variety of substances, making it a suitable replacement for aramid fibers and improving performance. However, direct composites of cellulose and aramid fibers perform poorly. Furthermore, under high voltage conditions, cellulose is flammable and prone to electrical treeing, which severely impacts the mechanical and safety properties of aramid insulation paper.

[0003] Currently, high-performance aramid insulation paper is primarily sourced from abroad, resulting in high costs and limited technology. Therefore, to address these shortcomings, we are currently working to develop aramid fiber composite insulation paper that is resistant to high-frequency partial discharge, high temperatures, and possesses comprehensive performance. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide an aramid insulation paper, a preparation method and an application.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing aramid insulation paper, comprising the following steps:

[0006] (1) washing meta-aramid short fibers with a treatment agent A until neutral to obtain a mixed solution, and dispersing the mixed solution with sodium polyacrylate to obtain a slurry suspension; the treatment agent A is at least one of a borate buffer and a boric acid buffer, and the pH value of the treatment agent A is 8.0-11.2;

[0007] (2) adding cellulose to a sulfamic acid solution for dispersion, heating for reaction, cooling, centrifugation for precipitation, and washing to obtain activated cellulose;

[0008] (3) mixing the treatment agent A, polyvinyl alcohol and the activated cellulose obtained in step (2), stirring and dispersing them to obtain a cellulose composite slurry;

[0009] (4) The slurry suspension obtained in step (1) and the cellulose composite slurry obtained in step (3) are mixed and dispersed to obtain a mixed slurry, which is then dehydrated, formed, and papered to obtain the aramid insulation paper.

[0010] The present invention utilizes treatment agent A to treat meta-aramid chopped fibers. After treatment with treatment agent A, the amide bonds in the molecular chains on the surface of the aramid fibers undergo micro-hydrolysis, generating carboxyl and amino groups that can form hydrogen bonds with hydroxyl groups on the surface of cellulose. Treatment with treatment agent A also alters the microscopic morphology and chemical structure of the meta-aramid chopped fibers. Spherical microstructures appear on the smooth surface of the meta-aramid chopped fibers, significantly increasing their surface roughness. Treatment with treatment agent A further enhances crosslinking between the meta-aramid chopped fibers.

[0011] The present invention utilizes treating agent A and aminosulfonic acid to jointly treat cellulose. The -NH2 bond in aminosulfonic acid can form a new hydrogen bond with the -OH bond on the plant fiber, thereby strengthening the interaction between cellulose molecules, enhancing the strength and toughness of cellulose, and at the same time, enhancing the thermal stability of cellulose.

[0012] During actual experiments, the inventors found that by using cellulose treated with treatment agent A and aminosulfonic acid in combination with meta-aramid short fibers treated with treatment agent A, aramid insulating paper with excellent mechanical properties and resistance to high-frequency partial discharge and high temperature can be obtained.

[0013] During actual experiments, the inventors discovered that a pH greater than 8 favors the distribution of boron on the aramid fiber surface, improving its dispersibility in solution. However, at pH levels exceeding 11.2, boron accumulates, hindering the formation of hydrogen bonds between surface carboxyl and amino groups and hydroxyl groups on the cellulose surface. Therefore, a pH between 8.0 and 11.2 allows for optimal dispersion of aramid fibers in the finished paper without affecting hydrogen bonding between surface groups, thereby enhancing tensile and electrical strength.

[0014] Preferably, in step (1), the borate buffer is one of borax-potassium dihydrogen phosphate buffer, borax-calcium chloride buffer, and borax-sodium carbonate buffer, and the boric acid buffer is one of boric acid-potassium chloride buffer and boric acid-potassium hydroxide buffer.

[0015] Preferably, in the step (1), the treatment agent A is treated at 20°C-35°C for 1h-2h; in the slurry suspension, the mass percentage of sodium polyacrylate is 0.1%-10%, the mass percentage of meta-aramid short fibers is 5%-10%, and the decomposition is treated at 20°C-35°C for 0.5h-2h.

[0016] Preferably, in step (2), the aminosulfonic acid solution is prepared using solvent 1, which is at least one of water, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0017] Preferably, in step (2), the mass percentage of the aminosulfonic acid solution is 1wt%-15wt%; and the mass ratio of the cellulose to the aminosulfonic acid is (10-50):(1-5).

[0018] Preferably, in step (2), the cellulose is at least one of bamboo pulp cellulose, bagasse pulp cellulose, bacterial cellulose, short cotton linter cellulose, and microcrystalline cellulose.

[0019] Preferably, the dispersion time is 5 min-60 min; the heating reaction temperature is 60°C-100°C, and the heating reaction time is 1 h-24 h; the centrifugal speed is 2000 r / min-8000 r / min, and the centrifugal time is 5 min-10 min; the washing solvent is at least one of water, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0020] Preferably, in step (3), the mass ratio of the treatment agent A, polyvinyl alcohol, and the activated cellulose obtained in step (2) is treatment agent A: polyvinyl alcohol: activated cellulose obtained in step (2) = (1-30): (1-10): (60-98).

[0021] Preferably, in step (4), the absolute dry mass of the cellulose composite pulp is 2%-10% of the absolute dry mass of the mixed pulp.

[0022] Preferably, in the step (4), the mixing and dispersing speed is 2500 r / min-5000 r / min; the papermaking temperature is 100° C.-200° C., the pressure is 8.0 MPa-10.0 MPa, and the time is 10 min-30 min.

[0023] In addition, the present invention provides aramid insulating paper prepared by the preparation method of aramid insulating paper.

[0024] Furthermore, the present invention provides application of the aramid insulation paper in the field of transformers.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention utilizes treatment agent A to treat meta-aramid chopped fibers. After treatment with treatment agent A, the amide bonds in the molecular chains on the surface of the aramid fibers undergo micro-hydrolysis, generating carboxyl and amino groups that can form hydrogen bonds with hydroxyl groups on the surface of cellulose. Treatment with treatment agent A also alters the microscopic morphology and chemical structure of the meta-aramid chopped fibers. Spherical microstructures appear on the smooth surface of the meta-aramid chopped fibers, significantly increasing their surface roughness. Treatment with treatment agent A further enhances crosslinking between the meta-aramid chopped fibers.

[0027] The present invention utilizes treating agent A and aminosulfonic acid to jointly treat cellulose. The -NH2 bond in aminosulfonic acid can form a new hydrogen bond with the -OH bond on the plant fiber, thereby strengthening the interaction between cellulose molecules, enhancing the strength and toughness of cellulose, and at the same time, enhancing the thermal stability of cellulose.

[0028] During actual experiments, the inventors found that by using cellulose treated with treatment agent A and aminosulfonic acid in combination with meta-aramid short fibers treated with treatment agent A, aramid insulating paper with excellent mechanical properties and resistance to high-frequency partial discharge and high temperature can be obtained. DETAILED DESCRIPTION

[0029] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below with reference to specific embodiments. Its purpose is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise specified, the experimental reagents and instruments designed for the implementation and comparative examples of the present invention are all commonly used ordinary reagents and instruments, which can be obtained from commercial channels. In the implementation and comparative examples, the experimental methods used are all conventional methods unless otherwise specified; and unless otherwise specified, the raw materials used in parallel experiments are the same batch of raw materials.

[0030] A method for preparing aramid insulating paper comprises the following steps:

[0031] (1) treating the meta-aramid short fibers with a treatment agent A at 20°C-35°C for 1 hour to 2 hours, washing them to neutrality to obtain a mixed solution, and dispersing the mixed solution with sodium polyacrylate at 20°C-35°C for 0.5 hour to 2 hours to obtain a slurry suspension;

[0032] The pH value of the treatment agent A is 8.0-11.2; the treatment agent A is at least one of a borate buffer and a boric acid buffer, the borate buffer is one of a borax-potassium dihydrogen phosphate buffer, a borax-calcium chloride buffer, and a borax-sodium carbonate buffer, and the boric acid buffer is one of a boric acid-potassium chloride buffer and a boric acid-potassium hydroxide buffer;

[0033] In the slurry suspension, the mass percentage of sodium polyacrylate is 0.1%-10%, and the mass percentage of meta-aramid short-cut fibers is 5%-10%;

[0034] (2) adding cellulose to a 1 wt% to 15 wt% sulfamic acid solution for dispersion, heating for reaction, cooling, centrifuging, and washing to obtain activated cellulose;

[0035] The mass ratio of the cellulose to the aminosulfonic acid is (10-50): (1-5);

[0036] The sulfamic acid solution is prepared using solvent 1, which is at least one of water, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide;

[0037] The cellulose is at least one of bamboo pulp cellulose, bagasse pulp cellulose, bacterial cellulose, short cotton linter cellulose and microcrystalline cellulose.

[0038] Preferably, the dispersion time is 5 min-60 min; the heating reaction temperature is 60°C-100°C, and the heating reaction time is 1 h-24 h; the centrifugal speed is 2000 r / min-8000 r / min, and the centrifugal time is 5 min-10 min; the washing solvent is at least one of water, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0039] (3) mixing the treatment agent A, polyvinyl alcohol and the activated cellulose obtained in step (2), stirring and dispersing them to obtain a cellulose composite slurry;

[0040] The mass ratio of the treatment agent A, polyvinyl alcohol, and the activated cellulose obtained in step (2) is treatment agent A: polyvinyl alcohol: activated cellulose obtained in step (2) = (1-30): (1-10): (60-98);

[0041] (4) The slurry suspension obtained in step (1) and the cellulose composite slurry obtained in step (3) are mixed and dispersed at a rotation speed of 2500 r / min-5000 r / min to obtain a mixed slurry, which is dehydrated, formed, and paper-made at a temperature of 100°C-200°C, a pressure of 8.0 MPa-10.0 MPa, and a time of 10 min-30 min to obtain the aramid insulating paper.

[0042] The absolute dry mass of the cellulose composite pulp is 2%-10% of the absolute dry mass of the mixed pulp.

[0043] Examples and Comparative Examples

[0044] Raw materials: Bamboo pulp cellulose: degree of polymerization 780, cellulose content greater than 85%, Beijing North Century Cellulose Technology Development Co., Ltd.; Bagasse pulp cellulose: industrial grade (bleached), Nanning Sugar Co., Ltd. Sugar and Paper Mill; Bacterial cellulose: diameter 50-100nm, Guilin Qihong Technology Co., Ltd.

[0045] Example 1

[0046] A method for preparing aramid insulating paper comprises the following steps:

[0047] (1) treating meta-aramid short fibers with treatment agent A at 25°C for 2 hours, washing them to neutrality to obtain a mixed solution, and dispersing the mixed solution with sodium polyacrylate at 25°C for 2 hours to obtain a slurry suspension;

[0048] The pH value of the treatment agent A is 11.0; the treatment agent A is a borax-sodium carbonate buffer solution;

[0049] In the slurry suspension, the mass percentage of sodium polyacrylate is 3%, and the mass percentage of meta-aramid short-cut fibers is 5%;

[0050] (2) adding cellulose to a 3 wt% sulfamic acid solution for dispersion, heating for reaction, cooling, centrifuging, and washing to obtain activated cellulose;

[0051] The mass ratio of cellulose to aminosulfonic acid is 30:5;

[0052] The sulfamic acid solution was prepared using solvent 1, which was N,N-dimethylformamide;

[0053] The cellulose is bamboo pulp cellulose.

[0054] Preferably, the dispersion time is 10 minutes; the heating reaction temperature is 100° C., and the heating reaction time is 2 hours; the centrifugal speed is 8000 r / min, and the centrifugal time is 5 minutes; and the washing solvent is N,N-dimethylformamide.

[0055] (3) mixing the treatment agent A, polyvinyl alcohol and the activated cellulose obtained in step (2), stirring and dispersing them to obtain a cellulose composite slurry;

[0056] The mass ratio of the treatment agent A, polyvinyl alcohol, and the activated cellulose obtained in step (2) is treatment agent A: polyvinyl alcohol: activated cellulose obtained in step (2) = 5:5:90;

[0057] (4) The slurry suspension obtained in step (1) and the cellulose composite slurry obtained in step (3) are mixed and dispersed at a rotation speed of 2500 r / min to obtain a mixed slurry, which is dehydrated, formed, and paper-made at a temperature of 100° C., a pressure of 10.0 MPa, and a time of 30 min to obtain the aramid insulating paper.

[0058] The absolute dry mass of the cellulose composite pulp is 2% of the absolute dry mass of the mixed pulp.

[0059] Example 2

[0060] A method for preparing aramid insulating paper comprises the following steps:

[0061] (1) treating meta-aramid short fibers with treatment agent A at 35°C for 1 hour, washing to neutrality to obtain a mixed solution, and dispersing the mixed solution with sodium polyacrylate at 35°C for 0.5 hour to obtain a slurry suspension;

[0062] The pH value of the treatment agent A is 11.0; the treatment agent A is a borax-sodium carbonate buffer solution;

[0063] In the slurry suspension, the mass percentage of sodium polyacrylate is 5%, and the mass percentage of meta-aramid short-cut fibers is 5%;

[0064] (2) adding cellulose to a 10 wt% sulfamic acid solution for dispersion, heating for reaction, cooling, centrifuging, and washing to obtain activated cellulose;

[0065] The mass ratio of the cellulose to the aminosulfonic acid is 10:1;

[0066] The sulfamic acid solution is prepared using solvent 1, which is dimethyl sulfoxide;

[0067] The cellulose is bagasse pulp cellulose.

[0068] The dispersion time is 60 minutes; the heating reaction temperature is 60° C., and the heating reaction time is 24 hours; the centrifugal speed is 6000 r / min, and the centrifugal time is 6 minutes; and the washing solvent is dimethyl sulfoxide.

[0069] (3) mixing the treatment agent A, polyvinyl alcohol and the activated cellulose obtained in step (2), stirring and dispersing them to obtain a cellulose composite slurry;

[0070] The mass ratio of the treatment agent A, polyvinyl alcohol, and the activated cellulose obtained in step (2) is treatment agent A: polyvinyl alcohol: activated cellulose obtained in step (2) = 5:5:90;

[0071] (4) The slurry suspension obtained in step (1) and the cellulose composite slurry obtained in step (3) are mixed and dispersed at a rotation speed of 3000 r / min to obtain a mixed slurry, which is dehydrated, formed, and paper-made at a temperature of 200° C., a pressure of 8.0 MPa, and a time of 10 min to obtain the aramid insulating paper.

[0072] The absolute dry mass of the cellulose composite pulp is 2% of the absolute dry mass of the mixed pulp.

[0073] Example 3

[0074] A method for preparing aramid insulating paper comprises the following steps:

[0075] (1) treating meta-aramid short fibers with treatment agent A at 30°C for 1.5 hours, washing them to neutrality to obtain a mixed solution, and dispersing the mixed solution with sodium polyacrylate at 30°C for 1 hour to obtain a slurry suspension;

[0076] The pH value of the treatment agent A is 11.0; the treatment agent A is a borax-sodium carbonate buffer solution;

[0077] In the slurry suspension, the mass percentage of sodium polyacrylate is 10%, and the mass percentage of meta-aramid short-cut fibers is 5%;

[0078] (2) adding cellulose to a 15 wt% sulfamic acid solution for dispersion, heating for reaction, cooling, centrifuging, and washing to obtain activated cellulose;

[0079] The mass ratio of cellulose to aminosulfonic acid is 30:5;

[0080] The sulfamic acid solution was prepared using solvent 1, which was dimethyl sulfoxide;

[0081] The cellulose is bacterial cellulose.

[0082] The dispersion time is 50 minutes; the heating reaction temperature is 70° C., and the heating reaction time is 18 hours; the centrifugal speed is 8000 r / min, and the centrifugal time is 5 minutes; and the washing solvent is dimethyl sulfoxide.

[0083] (3) mixing the treatment agent A, polyvinyl alcohol and the activated cellulose obtained in step (2), stirring and dispersing them to obtain a cellulose composite slurry;

[0084] The mass ratio of the treatment agent A, polyvinyl alcohol, and the activated cellulose obtained in step (2) is treatment agent A: polyvinyl alcohol: activated cellulose obtained in step (2) = 5:5:90;

[0085] (4) The slurry suspension obtained in step (1) and the cellulose composite slurry obtained in step (3) are mixed and dispersed at a rotation speed of 3000 r / min to obtain a mixed slurry, which is dehydrated, formed, and paper-made at a temperature of 150° C., a pressure of 8.0 MPa, and a time of 10 min to obtain the aramid insulating paper.

[0086] The absolute dry mass of the cellulose composite pulp is 2% of the absolute dry mass of the mixed pulp.

[0087] Example 4

[0088] Compared with the preparation method of the aramid insulating paper in Example 1, the only difference is that the selection of the treatment agent A in step (1) is different. Specifically, the pH value of the treatment agent A is 9.6; the treatment agent A is a boric acid-potassium chloride buffer solution; the remaining components, weight parts and preparation methods are exactly the same.

[0089] Example 5

[0090] Compared with the preparation method of the aramid insulating paper in Example 1, the only difference is that the selection of the treatment agent A in step (1) is different. Specifically, the pH value of the treatment agent A is 8.0; the treatment agent A is a borax-calcium chloride buffer solution; the remaining components, weight parts and preparation methods are exactly the same.

[0091] Example 6

[0092] Compared with the preparation method of the aramid insulation paper in Example 1, the only difference is that the mass percentage of the meta-aramid chopped fibers in the slurry suspension in step (2) is 10%; the remaining components, weight parts and preparation methods are exactly the same.

[0093] Example 7

[0094] Compared with the preparation method of the aramid insulating paper in Example 1, the only difference is that the mass ratio of treatment agent A: polyvinyl alcohol: activated cellulose obtained in step (2) in step (3) is 15:10:75; the remaining components, weight parts and preparation methods are exactly the same.

[0095] Example 8

[0096] Compared with the preparation method of the aramid insulation paper in Example 1, the only difference is that the absolute dry mass of the cellulose composite slurry in step (4) is 5% of the absolute dry mass of the mixed slurry; the other components, weight parts and preparation methods are exactly the same.

[0097] Example 9

[0098] Compared with the preparation method of the aramid insulation paper in Example 1, the only difference is that the absolute dry mass of the cellulose composite slurry in step (4) is 10% of the absolute dry mass of the mixed slurry; the other components, weight parts and preparation methods are exactly the same.

[0099] Comparative Example 1

[0100] Compared with the preparation method of the aramid insulating paper in Example 1, the only difference is that the selection of the treatment agent A in step (1) is different. Specifically, the pH value of the treatment agent A is 11.0; the treatment agent A is a sodium phosphate-disodium hydrogen phosphate buffer solution; the remaining components, weight parts and preparation methods are exactly the same.

[0101] Comparative Example 2

[0102] Compared with the preparation method of the aramid insulating paper in Example 1, the only difference is that the selection of the treatment agent A in step (1) is different. Specifically, the pH value of the treatment agent A is 7.6; the treatment agent A is potassium dihydrogen phosphate-sodium hydroxide buffer; the remaining components, weight parts and preparation methods are exactly the same.

[0103] Comparative Example 3

[0104] Compared with the preparation method of the aramid insulating paper in Example 1, the only difference is that the selection of the treatment agent A in step (1) is different. Specifically, the pH value of the treatment agent A is 6.0; the treatment agent A is acetic acid-sodium acetate buffer; the remaining components, weight parts and preparation methods are exactly the same.

[0105] Comparative Example 4

[0106] Compared with the preparation method of the aramid insulation paper in Example 1, the only difference is that the absolute dry mass of the cellulose composite slurry in step (4) is 1% of the absolute dry mass of the mixed slurry; the other components, weight parts and preparation methods are exactly the same.

[0107] Comparative Example 5

[0108] Compared with the preparation method of the aramid insulation paper in Example 1, the only difference is that the absolute dry mass of the cellulose composite slurry in step (4) is 15% of the absolute dry mass of the mixed slurry; the other components, weight parts and preparation methods are exactly the same.

[0109] Performance Testing

[0110] The thickness, tensile strength and electrical strength tests are carried out in accordance with GB / T 29627.2-2013 "Polyaramide fiberboard for electrical purposes Part 2: Test methods" and GB / T20629.3-2019 "Non-cellulose paper for electrical purposes Part 3: Unfilled polyaramide fiber paper".

[0111] The test results are shown in Table 1.

[0112] Table 1

[0113]

[0114]

[0115] As can be seen from the above table, the aramid composite insulating paper prepared in the embodiment of the present invention has a tensile strength of more than 50 MPa and an electrical strength of more than 25 kV / mm. The present invention uses cellulose treated with treatment agent A and aminosulfonic acid in combination with meta-aramid chopped fibers treated with treatment agent A to obtain aramid insulating paper with excellent mechanical properties and resistance to high-frequency partial discharge and high temperature.

[0116] From the comparison between Example 1, Examples 4-5, and Comparative Examples 1-3, it can be seen that when the pH value of the treating agent A is 8.0-11.2, the tensile strength and electrical strength of the prepared aramid composite insulating paper are better.

[0117] From the comparison of Example 1, Examples 8-9, and Comparative Examples 4-5, it can be seen that when the absolute dry mass of the cellulose composite slurry in step (4) is 2%-10% of the absolute dry mass of the mixed slurry, the tensile strength and electrical strength of the aramid composite insulating paper finally prepared are both high. If the proportion of cellulose is too small, the tensile strength and electrical strength will be seriously reduced. If the proportion of cellulose is too high, the cellulose content is too high, and the cellulose itself will have a negative impact on the tensile strength and electrical strength. Therefore, the inventors found in the actual experimental process that when the absolute dry mass of the cellulose composite slurry is 2%-10% of the absolute dry mass of the mixed slurry, the tensile strength and electrical strength of the aramid composite insulating paper finally prepared are both high.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing aramid insulation paper, characterized in that: The following steps are involved: (1) Washing the meta-aramid chopped fibers with a treatment agent A until neutral to obtain a mixed solution, and dispersing the mixed solution with sodium polyacrylate to obtain a slurry suspension; The treatment agent A is at least one of a borate buffer and a boric acid buffer, and the pH value of the treatment agent A is 8.0-11.2; (2) Add cellulose to aminosulfonic acid solution for dispersion, heat for reaction, cool, centrifuge and precipitate, and wash to obtain activated cellulose; (3) mixing the treatment agent A, polyvinyl alcohol and the activated cellulose obtained in step (2), stirring and dispersing them to obtain a cellulose composite slurry; (4) The slurry suspension obtained in step (1) and the cellulose composite slurry obtained in step (3) are mixed and dispersed to obtain a mixed slurry, which is then dehydrated, formed, and papered to obtain the aramid insulating paper; the absolute dry mass of the cellulose composite slurry is 2%-10% of the absolute dry mass of the mixed slurry.

2. The method for preparing aramid insulating paper according to claim 1, wherein: In the step (1), the borate buffer is one of borax-potassium dihydrogen phosphate buffer, borax-calcium chloride buffer, and borax-sodium carbonate buffer, and the boric acid buffer is one of boric acid-potassium chloride buffer and boric acid-potassium hydroxide buffer.

3. The method for preparing aramid insulation paper according to claim 1, wherein: In the step (1), the treatment agent A is treated at 20°C-35°C for 1h-2h; in the slurry suspension, the mass percentage of sodium polyacrylate is 0.1%-10%, the mass percentage of meta-aramid short-cut fibers is 5%-10%, and the debonding is treated at 20°C-35°C for 0.5h-2h.

4. The method for preparing aramid insulating paper according to claim 1, wherein: In the step (2), the mass percentage of the aminosulfonic acid solution is 1wt%-15wt%; the mass ratio of the cellulose to the aminosulfonic acid is (10-50): (1-5).

5. The method for preparing aramid insulation paper according to claim 1, wherein: In the step (3), the mass ratio of the treatment agent A, polyvinyl alcohol, and the activated cellulose obtained in the step (2) is treatment agent A: polyvinyl alcohol: activated cellulose obtained in the step (2) = (1-30): (1-10): (60-98).

6. The method for preparing aramid insulation paper according to claim 1, wherein: In the step (4), the rotation speed of the mixing and dispersing is 2500 r / min-5000 r / min; the temperature of the papermaking is 100° C.-200° C., the pressure is 8.0 MPa-10.0 MPa, and the time is 10 min-30 min.

7. Aramid insulating paper prepared by the method for preparing aramid insulating paper according to any one of claims 1 to 6.

8. Use of the aramid insulation paper according to claim 7 in the field of transformers.

Images